provide a weather enclosure above the outlet plenum. However, enclose
hoppers within a bottom weather enclosure. Plenum height shall be
[minimum\^ 305 mm^\~ one foot~\ greater in height than bags] [minimum
4.50 meters 15 feet when using 4.30 meters 14 feet bags] to provide an
indoor bag replacement area. Conform to SMACNA Arch. Manual. Include
lighting. Seal joints by continuous fillet or complete penetration groove
welds. Do not use caulking. Design enclosure to withstand differential
thermal expansion between housing and weather enclosure. Design plenum to
support minimum 4.8 kPa 100 psf. Space roof purlins so that roof deck span
will not exceed 2.13 meters 7 feet. Provide additional support for
equipment placed on the roof. Slope and extend top surface and top
surfaces of appurtenant structures, by not less than 25 mm one inch beyond
side insulation, to allow water runoff and to prevent pooling. Provide a
safety rail around the top perimeter surface, a 80 mm 3 inch fascia rain
barrier of 6 mm 1/4 inch ASTM A 242/A 242M steel plate, a 80 mm 3 inch
kickplate of 6 mm 1/4 inch ASTM A 242/A 242M steel plate, and drain holes
to permit water runoff.
]2.7
BAG CLEANING SYSTEM
2.7.1
General
Clean bags by [reverse air] [pulse jet]. Clean one compartment at a time
on a predetermined adjustable programmed cycle or when the differential
pressure across the bags reaches a set point. Provide 50 mm 2 inch capped
pressure taps with rod-outs on each side of the tube sheet, accessible from
the access platforms, to measure differential pressure. Connect pressure
taps to remote indicators in the control room using minimum 10 mm 3/8 inch
stainless steel tubing. Provide tubing with three-way valves, adjacent to
the pressure indicators within the control room panel, to allow cleaning of
the pressure lines with compressed air.
[2.7.2
Reverse Air Cleaning System
Provide each baghouse with a reverse air cleaning system including two
reverse air fans, connecting ductwork, dampers, valves, and automatic
controls. Bags shall gradually reinflate after cleaning. Use air from the
outlet manifold for reverse air cleaning and to maintain the reverse air
ductwork temperature above the dewpoint temperature. Thimbles for 200 mm
8 inch diameter bags shall be of 12 Gage carbon-steel plate, one nominal
bag diameter in length, and spaced not less than 241 mm 9 1/2 inch on
centers. Thimbles for 300 mm 12 inch diameter bags shall be of 12 Gage
carbon-steel plate, one nominal bag diameter in length, and spaced not less
than 356 mm 14 inch on centers. Thimbles shall be inline, not staggered.
Tubesheet and bag alignment shall be within 3 mm 1/8 inch for plumb.
2.7.2.1
Reverse Air Fans
**************************************************************************
NOTE: One fan is sufficient for most applications.
However, two fans, each rated at 100 percent of
required capacity, may be required where increased
reliability, logistics, or service dictate.
**************************************************************************
Provide two heavy duty 100 percent capacity industrial reverse air fans;
one fan shall be placed on standby while the other fan is operational. Each
fan shall have a single flanged inlet, a single flanged outlet, and an
automatically operated louver damper. Louver dampers shall be as specified
SECTION 15863N
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